also add a test to map_identity

Author: ada4a

tests/ui/map_identity.fixed

@@ -87,3 +87,15 @@ fn issue13904() {
     let _ = { it }.next();
     //~^ map_identity
 }
+
+// same as `issue11764`, but for arrays
+fn issue15198() {
+    let x = [[1, 2], [3, 4]];
+    // don't lint: `&[i32; 2]` becomes `[&i32; 2]`
+    let _ = x.iter().map(|[x, y]| [x, y]);
+    let _ = x.iter().map(|x| [x[0]]).map(|[x]| x);
+
+    // no match ergonomics for `[i32, i32]`
+    let _ = x.iter().copied();
+    //~^ map_identity
+}

tests/ui/map_identity.rs

@@ -93,3 +93,15 @@ fn issue13904() {
     let _ = { it }.map(|x| x).next();
     //~^ map_identity
 }
+
+// same as `issue11764`, but for arrays
+fn issue15198() {
+    let x = [[1, 2], [3, 4]];
+    // don't lint: `&[i32; 2]` becomes `[&i32; 2]`
+    let _ = x.iter().map(|[x, y]| [x, y]);
+    let _ = x.iter().map(|x| [x[0]]).map(|[x]| x);
+
+    // no match ergonomics for `[i32, i32]`
+    let _ = x.iter().copied().map(|[x, y]| [x, y]);
+    //~^ map_identity
+}

tests/ui/map_identity.stderr

@@ -87,5 +87,11 @@ error: unnecessary map of the identity function
 LL |     let _ = { it }.map(|x| x).next();
    |                   ^^^^^^^^^^^ help: remove the call to `map`
 
-error: aborting due to 13 previous errors
+error: unnecessary map of the identity function
+  --> tests/ui/map_identity.rs:105:30
+   |
+LL |     let _ = x.iter().copied().map(|[x, y]| [x, y]);
+   |                              ^^^^^^^^^^^^^^^^^^^^^ help: remove the call to `map`
+
+error: aborting due to 14 previous errors